The invention relates to a spinning machine and a process for operating a spinning machine having a plurality of spinning stations spinning yarn from slivers and having transport devices for removing the slivers from cans and for feeding them to the spinning stations, and to a spinning machine.
It is known in the case of an open-end spinning machine (German Patent Document DE-C 23 35 740) to arrange cans with the slivers to be spun on a platform above the spinning machine. The slivers are withdrawn by way of feeding rollers and are guided downward through perpendicular tubes to the spinning stations.
It is also known (British Patent Document 1 183 208) to feed the fiber material to be spun in the form of slivers to a ring spinning machine. In the case of this construction, the slivers are deposited in cans which are placed on a platform above the ring spinning machine. By way of feeding rollers, the sliver are guided to essentially perpendicularly extending guiding tubes in which they are guided to the drafting units of the individual spinning stations.
It is also known (British Patent Document 1 015 780) to feed slivers to the spinning stations of a ring spinning machine which are fed in cans. In the case of this construction, the cans are deposited in front of the spinning machine while leaving an operating aisle. By way of guiding rollers, the slivers are withdrawn from the cans and then are taken over by respective pairs of conveyor belts which guide the slivers to the drafting units of the spinning stations.
In the case of ring spinning machines, the feeding of slivers by means of cans has not found acceptance in practice. In order to obtain the desired fine yarn size, the drafting units must operate with high drafts. Since, however, in the case of ring spinning, the maximal delivery speed is limited at the outlet of the drafting units, this has the result that the feeding roller pairs of the drafting units must rotate at very low rotational speeds, that is, at rotational speeds of less than 1 min.sup.-1 (one revolution per minute). In the case of long machines with a plurality of spinning stations, however, such low rotational speeds constructively cannot be implemented with acceptable expenditures in such a manner that the feeding roller pairs rotate at a uniform rotational speed. A non-uniform jerky rotation of the feeding roller pairs leads to irregular drafting in the slivers so that the spun yarn does not have a satisfactory quality.
According to an older German Patent Application (P 40 41 112.5), which is no prior publication, it is provided to feed finer slivers than previously particularly to ring spinning machines, that is, slivers of a fineness of approximately Nm 0.4 to approximately Nm 0.8. This has the result that the overall drafting of the drafting units can be reduced so that, despite the maximal delivery speed at the delivery roller pair of the drafting units, it is ensured that the feeding roller pairs of these drafting units rotate at sufficiently high rotational speeds which permit a rotation without any jerking. In the case of this construction, the fine slivers are guided from the cans to the spinning stations by means of transport devices in such a manner that no faulty drafting occurs during the transport.
It is an object of the invention to provide a process by means of which the operating of a spinning machine of the initially mentioned type is improved, particularly of a spinning machine which processes fine slivers in the range of from approximately Nm 0.4 to approximately Nm 0.8.
This object is achieved in that, for the preparation of the start spinning of the spinning machine, the transport devices are first switched on, then the slivers are placed in the transport devices and are fed by means of the transport devices to receiving devices situated in the area of the spinning stations, from which the slivers are removed and are placed in the spinning stations which are then started.
By means of this construction, the operation of a spinning machine is improved mainly because of the fact that a first start is improved, that is, a first starting of the spinning machine or a starting after a change of batches. In this case, new slivers must be fed to the spinning stations at all spinning stations. In the case of the process according to the invention, the slivers are successively placed in the transport devices assigned to the individual spinning stations, after which the slivers are then fed to the receiving devices which serve as a type of an intermediate storage device. After all slivers have been inserted, the slivers are taken out of the receiving devices and are placed in the spinning stations. Then, all spinning stations may be started simultaneously. Since the feeding speeds at which the slivers are guided by the transport devices out of the cans to the spinning stations, are relatively low, also in the case of a spinning machine having a plurality of spinning stations, no significant differences of length occur in the lengths of the slivers withdrawn from the cans, which slivers are successively placed in the individual transport devices. This has the advantage that the slivers of the individual cans are used up essentially simultaneously so that then also an essentially simultaneous change of all cans can be carried out.
Since the inserting of the slivers into the spinning stations is also carried out successively at the individual spinning stations, it is advantageous, in a further development of the invention, to switch the transport devices off again before the inserting of the slivers into the spinning stations and to switch them on again after the inserting when the spinning machine is started. Thus it is ensured that, during the time of the inserting of the slivers in the individual spinning stations, no varying lengths of slivers are removed from the cans. It is therefore possible that such a spinning machine is started only by the work of a single operator without any resulting significant differences in the lengths of the slivers withdrawn from the cans and without an excessive loss of fiber material during the start of the operation.
For carrying out the process, it is provided in the case of a spinning machine having several spinning stations for the spinning of slivers into a yarn and having transport devices for the removal of the slivers from the cans and for the guiding to the spinning stations, that the transport devices are followed by devices for the receiving of the slivers which are arranged outside the normal travelling path of the slivers from the transport devices to the spinning stations.
During a first start of the spinning machine, which naturally also includes a start after a batch change, the slivers travel into the devices for the receiving so that they are located at a defined point and also project out of the transport devices by a minimum length so that subsequently they can be introduced into the spinning stations, and particularly can be placed in the drafting units of these spinning stations. The slivers are therefore in each case located at defined points which are assigned to the individual spinning stations.
In a further development of the invention, it is provided that, below the transport devices, which feed the slivers from above downward to the spinning stations, devices are arranged for receiving the slivers. Thus, it is ensured that the slivers, already by virtue of their gravity, arrive at the devices for the receiving from the transport devices.
In a further development of the invention, it is provided that the devices for the receiving of the slivers are connected to a collecting device. In many cases, it will be necessary to cut the slivers, which are guided from the transport devices to the devices for the receiving, to a uniform length before the inserting into the spinning stations. The excess parts of the slivers will then be received by the collecting device so that they can be removed and may possibly be used again. In this case, it is expedient for the devices for the receiving of the slivers to be constructed as a device which extends over several spinning stations and in the longitudinal direction of the machine. As a result, the collecting of the sliver residues at one point will be facilitated.
In a further development of the invention, it is provided that the devices for the receiving of the slivers are arranged in the machine center of a two-sided spinning machine and are assigned to the spinning stations of both sides of the machine. As a result, only relatively low expenditures are required with respect to equipment.
In a further development of the invention, it is provided that the devices for the receiving of the slivers are developed as a trough which extends in the longitudinal direction of the machine and is open toward the top. As a result, it is possible to create purely mechanical devices for catching the slivers fed by the transport devices where the danger of an operational disturbance is very low.
In a further development of the invention, it is provided that the bottom of the trough is equipped with a conveyor belt extending in the longitudinal direction of the machine. This conveyor belt, which is driven continuously or preferably discontinuously, has the purpose of conveying the excess lengths of the slivers to a collecting device which is preferably arranged at a machine end.
In the case of another embodiment, it is provided that the trough, in its bottom area, is preferably provided with closable intake devices. By means of these intake devices, of which preferably one respectively is assigned to a spinning station, it is possible to make the slivers available at precisely defined points so that they can also be taken over in a simple manner by an automatic device which carries out the inserting into the spinning stations. When the intake devices are closable, this has the advantage that they can be made inoperative when they are not needed, that is, during the normal spinning operation.
In another development of the invention, it is provided that the devices for the receiving of the slivers are constructed as suction devices aimed at the area of the transport devices which delivers the slivers. These suction devices, of which preferably one respectively is assigned to one spinning station, also provide that the slivers are made available at defined points.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.